Cutting insert for profile turning, as well as assembly with cutting insert and cassette

Abstract

Cutting insert (10) for profile turning, in particular for wheel profile turning, comprising a top surface (12), a bottom surface (14) and side surfaces (16), wherein at the transition from the top surface (12) to the side surfaces (16) two cutting edges (22a, 22b) for machining a workpiece (48) and two further edges (18a, 18b) each with two ends (18a', 18a'', 18b', 18b'') are formed, wherein the two cutting edges (22a, 22b) are each formed as partial circles without interruption and have a full radius, wherein each of the two cutting edges (22a, 22b) covers an angular range of approximately 180°, so that a defined line contact results between each of the cutting edges (22a, 22b) and a workpiece (48) to be machined, which is independent of the relative position of the cutting insert (10) to the workpiece. workpiece (48) is wherein the cutting edges (22a, 22b) each extend from one end (18a', 18a'', 18b', 18b'') of one of the two edges (18a, 18b) to the opposite end (18a',18a'', 18b', 18b'') of the other of the two edges (18a, 18b), wherein the transition from the underside (14) to the side surfaces (16) is formed analogously to the transition from the top surface (12) to the side surfaces (16), so that the cutting insert (10) comprises four semicircular cutting edges (22a, 22b, 24a, 24b).

Description

[0001] The invention relates to a cutting insert for profile turning, in particular for wheel profile turning, and to an assembly comprising such a cutting insert and a cassette for receiving the cutting insert, which can be attached to a machine tool.

[0002] Such a cutting insert and its associated cassette can be used for reconditioning used and new wheels, especially traction wheels. The cutting insert is held in the cassette, which is attached to a machine tool. The machine tool moves the cassette and the cutting insert along the wheel. The machine tool moves the cutting insert along the tread surface to the flange surface and then along the flange surface. The cutting insert has at least one cutting edge for removing worn material from the tread and flange surfaces. This cutting edge is moved directly along the tread and flange surfaces. The cutting depth and the chip-breaking characteristics of the cutting insert can be adjusted by modifying the design of the cutting edge, the corresponding surface of the cutting insert, and the areas adjacent to the cutting edge.

[0003] It has proven problematic that the worn material to be removed, which is present on the tread and the flange surface, has a different thickness, resulting in different requirements for the cutting insert, its cutting depth, and chip formation. This is particularly true at the transition from the tread to the flange surface, as chip control is especially difficult in this area. It is also not always possible to remove all the material in a single pass, so it is necessary to reposition and re-position the cutting insert to machine first the tread and then the flange surface. One or more complete cutting passes are also possible.

[0004] Cutting inserts are known from DE 103 46 790 A1 and DE 16 52 678 B.

[0005] It is therefore an object of the invention to enable the efficient reworking of a workpiece and in particular of a wheel rim of a railway wheel.

[0006] The object of the invention is achieved by a cutting insert for profile turning, in particular for wheel profile turning, which comprises a top surface, a bottom surface, and side surfaces, wherein at the transition from the top surface to the side surfaces two cutting edges for machining a workpiece and two further edges, each with two ends, are formed, wherein the two cutting edges are each formed as partial circles without interruption and have a full radius. Each of the two cutting edges covers an angular range of approximately 180°, so that a defined line contact is established between each of the cutting edges and a workpiece to be machined, which is independent of the relative position of the cutting insert to the workpiece. The cutting edges extend from one end of one of the two edges to the opposite end of the other of the two edges.Furthermore, the transition from the underside to the side surfaces is designed analogously to the transition from the top to the side surfaces, so that the cutting insert comprises four semicircular cutting edges. This allows the cutting insert to continue to be used even if one of the cutting edges becomes worn, by simply turning it over and using a cutting edge on the other side.

[0007] Because the cutting edges formed on the cutting insert are semicircular without interruption and thus have a full radius, it is possible to machine a wheel, i.e., the running surface and the flange surface, in a single pass without repositioning the cutting insert. The advantages are primarily evident at the transition between the running surface and the flange surface, as a cutting edge with a full radius allows for improved chip control. This is because the angle of attack of the cutting edge on the surface of the workpiece being machined is identical across the entire cutting edge due to the semicircular design with a full radius, and therefore independent of the relative position of the workpiece surface to the cutting edge. Furthermore, the cutting insert according to the invention can be used to machine a wheel using various techniques, such as profile turning and facing.In particular, the cutting insert according to the invention makes it possible to perform a re-forming turning of the wheels. Thus, the wheels can be machined particularly efficiently and according to requirements using the cutting insert according to the invention.

[0008] Depending on the size of the cutting insert and the selected cutting edge radius, correspondingly large cutting surfaces, cutting lines or cutting points result in the contact area of ​​the cutting edge on the workpiece, with which precise reworking of the wheels is possible.

[0009] Because the semicircular cutting edges cover an angular range of approximately 180° and are therefore semicircular in shape, the transition from the cutting edge to the edge is smooth, i.e., without a corner or point.

[0010] Another aspect of the invention provides that the edges are straight, in particular parallel to each other. This results in two straight and parallel side surfaces which can serve as a contact surface in a cassette, the inner part of which can be recessed. The straight side surfaces allow for a large contact area, enabling high forces to be transferred from the cutting insert to the cassette that holds the cutting insert.

[0011] A further aspect of the invention provides that the upper and / or lower surface is mirror-symmetrical with respect to its central longitudinal and / or transverse axis, in particular point-symmetrical with respect to the center point. Due to the symmetrical design of the upper and / or lower surface, the cutting insert can be used as a reversible cutting insert, since it can be rotated 180° in the plane of the upper and / or lower surface, thereby allowing at least two cutting edges to be used in the same cassette.

[0012] According to a further aspect of the invention, the cutting insert is mirror-symmetrical with respect to its central longitudinal and / or transverse axis, and in particular point-symmetrical with respect to the center point. A cutting insert designed in this way can even be used four times, since it can be rotated 180° in the plane of the top or bottom surface, i.e., the longitudinal axis of the cutting insert, as well as around the transverse axis of the cutting insert. This results in a total of four different installation positions, so that all four cutting edges can be used. This significantly increases the service life of a cutting insert.

[0013] Another aspect of the invention provides that an opening is provided in the side surfaces where the edges are formed, which interacts with a fastening mechanism. The cutting insert is attached to the cassette via this fastening mechanism, in particular in a receiving pocket of the cassette.

[0014] According to a further aspect of the invention, chip breakers are provided on the semicircular cutting edges and / or on the edges. These chip breakers, also known as chip breakers or chip splitters, ensure that the removed chip cannot become jammed in the machine tool, as it is split or broken after a certain length and thus guided away from the machine tool. The chip breakers can be designed differently, for example, for roughing or finishing.

[0015] Furthermore, the problem is solved by an assembly comprising a cutting insert according to the invention and a cassette that can be attached to a machine tool and includes a receiving pocket for the cutting insert, with which a workpiece having a rotational axis can be machined. The receiving pocket has a main contact surface against which a side surface of the cutting insert rests, the main contact surface having a plane angle greater than 90° to the rotational axis of the workpiece, in particular a plane angle of 93°. With the cassette, an inserted cutting insert, in particular via its transverse axis, abuts the running surface of the wheel at a steeper angle, which also has an angle to the rotational axis of the workpiece. Previously, the cassettes were designed such that the main contact surface had an angle to the rotational axis that compensated for the angle between the running surface and the rotational axis, i.e., less than 90°.This was necessary because the cutting edge was not formed with a full radius and was therefore not semicircular. However, this led to problems at the transition from the tread to the flange surface, as the angle of the surface to be machined relative to the axis of rotation changes there. The inventive design of the cassette ensures that worn material at the transition from the tread to the flange surface can be removed safely and in a controlled manner. The chip breaking properties at the transition from the tread to the flange surface, as well as on the flange of the wheel itself, are also significantly improved by this cassette design. These advantages are even more pronounced when using a cutting insert with a full-radius cutting edge.

[0016] Another aspect of the invention provides that the cassette has a second contact surface that is perpendicular to the main contact surface. The second contact surface improves the precise positioning of the cutting insert in the cassette, particularly in its receiving pocket, as well as the secure storage of the cutting insert in the receiving pocket.

[0017] According to one aspect of the invention, part of the fastening mechanism for securing the cutting insert is provided on the main contact surface. The cutting insert is predominantly attached to the main contact surface, which is larger than the second contact surface, thereby improving the secure storage of the cutting insert in the holder.

[0018] A further aspect of the invention provides that the central axis of the fastening mechanism component has an angle other than 90° to the main contact surface. This inclined orientation of the fastening mechanism component ensures that, during fastening, the cutting insert is drawn not only against the main contact surface but also against the secondary contact surface, thus reaching its predetermined position. The fastening mechanism component can be designed as a tension pin.

[0019] Further advantages and features of the invention will become apparent from the following description and the drawings, to which reference is made. The drawings show: - Fig. 1 a side view of the cutting insert according to the invention, - Fig. 2 a top view of the cutting insert Fig. 1, - Fig. 3 a perspective detail view of the top of the cutting insert from the Fig. 1 and Fig. 2, - Fig. 4 a top view of the cassette of the assembly according to the invention, - Fig. 5 a side view of the cassette Fig. 4, - Fig. 6 a perspective view of the assembly according to the invention with the cassette made of the Fig. 4 and Fig. 5, in which the cutting insert is made from the Fig. 1 and Fig. 2 is recorded, - Fig. 7 the assembly from Fig. 6 in top view, - Fig. 8 a side view of the assembly from the Fig. 6 and Fig. 7, - Fig. 9 a part of a machine tool with attached cassette and cutting insert held therein during machining of a wheel at a first time A, - Fig. 10 the arrangement from Fig. 9 to a second time B, and - Fig. 11 the arrangement from the Fig. 9 and Fig. 10 at a third point in time C.

[0020] In Fig. Figure 1 shows a cutting insert 10 in a side view. The cutting insert 10 has a top surface 12 and a bottom surface 14, which are connected to each other via side surfaces 16. In Fig. Figure 1 shows one side surface 16a completely and two further side surfaces 16b, 16c partially. The cutting insert 10 also has another side surface 16d opposite side surface 16a, which is shown in Fig. 1 is not visible.

[0021] An edge 18a is formed at the transition from the top surface 12 to the side surface 16a, and an edge 20a is formed at the transition from the bottom surface 14 to the side surface 16a. Furthermore, a cutting edge 22a, 22b is formed at the transition from the top surface 12 to the side surface 16b and to the side surface 16c, and a further cutting edge 24a, 24b is formed at the transition from the bottom surface 14 to the side surfaces 16b, 16c.

[0022] Furthermore, at the transition from the top surface 12 to the side surface 16d and at the transition from the bottom surface 14 to the side surface 16d, an additional edge 18b is formed, which in Fig. 1, however, are not visible.

[0023] The cutting insert 10 also has an opening 26 in the side surface 16a, which extends through the entire cutting insert 10 to the opposite side surface 16d. The opening 26 serves to attach the cutting insert 10 to a cassette (not shown here).

[0024] Furthermore, the cutting insert 10 is mirror-symmetrical to its longitudinal axis LS and its transverse axis QS, which results in the cutting insert 10 being point-symmetrical with respect to its center MS.

[0025] The cutting insert 10 made of Fig. 1 is in Fig. 2 shown in a top view of the upper surface 12. From the Fig. Figure 2 shows that the upper surface 12 forms two straight and parallel edges 18a, 18b and two semicircular cutting edges 22a, 22b facing the respective side surfaces 16. The two cutting edges 22a, 22b merge into edges 18a, 18b at correspondingly opposite ends. Cutting edge 22a connects a first end 18a' of edge 18a with the opposite first end 18b' of the other edge 18b, and cutting edge 22b connects a second end 18a'' of edge 18a with the opposite second end 18b'' of the other edge 18b. Due to the semicircular shape of the cutting edges 22a, 22b, the cutting insert has 10 cutting edges 22a, 22b which have a full radius and cover an angular range of about 180°.

[0026] Chip control steps 28 and 30 are assigned to the cutting edges 22a and 22b, as well as to edges 18a and 18b. The chip removed during machining of a workpiece, such as a cutting edge, can be controlled via the chip control steps 28 and 30. The chip control steps 28 assigned to the cutting edges 22a and 22b can have a different structure than the chip control steps 30 assigned to edges 18a and 18b, resulting in different chip breaking properties. The chip control steps 28 are in Fig. 3 shown in detail in a perspective view.

[0027] The upper surface 12 of the cutting insert 10 is designed like the lower surface 14, so that the lower surface 14 has a correspondingly identical arrangement and structure.

[0028] The top and bottom surfaces 12, 14 are both mirror-symmetric with respect to their longitudinal axis L and their transverse axis Q. This means that the top and bottom surfaces 12, 14 are each point-symmetric with respect to their respective centers M.

[0029] In the Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. Figure 8 shows a cassette 32, which serves to hold the cutting insert 10, wherein in the Fig. 6, Fig. 7 to Fig. 8 shows the cassette 32 with the cutting insert 10 inserted.

[0030] The cassette 32 has a receiving pocket 34 that receives the cutting insert 10. The receiving pocket 34 is formed by a main contact surface 36 and a second contact surface 38, against which the inserted cutting insert 10 rests with two of its side surfaces 16.

[0031] The receiving pocket 34 is arranged within the cassette 32 such that it is inclined in the plane to the general orientation G of the cassette 32, which is perpendicular to the axis of rotation D of the workpiece to be machined ( Fig. 4) Therefore, the main mounting surface 36 has an angle α to the axis of rotation D that is greater than 90°. The in Fig. The straight line shown as axis D in figure 4 is a straight line shifted parallel to the actual axis D, thus serving as a guide.

[0032] The cassette 32 has a fastening mechanism for securing the cutting insert 10 in its receiving pocket 34, which is partly formed by a fastening opening 40 below the receiving pocket 34 and a fastening opening 42 on the main contact surface 36 ( Fig. 5) Furthermore, part of the fastening mechanism is designed as a tension pin 43, which can be arranged on the main contact surface 38 of the cassette 32, in particular in the fastening opening 42 ( Fig. 4).

[0033] After inserting the cutting insert 10, it is attached to the cassette 32 inside the receiving pocket 34 by a fastening element 44 which triggers the fastening mechanism and is inserted into the fastening opening 40 ( Fig. 6-8). The clamping pin 43 extends through the opening 26 of the cutting insert 10, which is inserted into the receiving pocket 34, and secures the cutting insert 10 by means of this pin. The central axis of the clamping pin 43 has an angle other than 90° to the main contact surface 36. This causes the cutting insert 10 to be drawn against the main contact surface 36 with one of the straight edges 18, 20 and its corresponding side surface 16a, 16d, and with part of one of the side surfaces 16b, 16c against the second contact surface 38, thus achieving precise positioning of the cutting insert 10 on the cassette 32.

[0034] In the Fig. In the arrangement shown in Figure 7, the side surface 16d assigned to the edges 18b and a part of the side surface 16b are drawn to the main mounting surface 36 and the second mounting surface 38, respectively.

[0035] Due to the relative position of the receiving pocket 34 to the cassette 32, the transverse axis QS of the cutting insert 10, the transverse axes Q of the top and bottom surfaces 12, 14 and the side surfaces 16a, 16d also have the angle α to the axis of rotation D of the workpiece to be machined, which is greater than 90° ( Fig. 7). The in Fig. Line 7, represented as axis of rotation D, is also a line shifted parallel to axis of rotation D.

[0036] The cassette 32 is basically designed so that it has typical dimensions based on the basic dimensions, which allows it to be used in existing machine tools and their holders.

[0037] In the Fig. Figures 9-11 show how the cassette 32, including the cutting insert 10, is inserted into a holder 46 of a machine tool. The holder 46 shown here actually has two cassettes 32, each with a cutting insert 10. A workpiece 48 to be machined, in the form of a pulley wheel, is also shown, which has a running surface 50 and a flange surface 52. The axis of rotation D of the workpiece 48 is also shown.

[0038] During operation of the traction wheel 48, wear patterns 54 have formed on the running surface 50 and the flange surface 52. These are repaired during reconditioning using the cutting insert 10 by removing a layer of the traction wheel 48, thus restoring a smooth running surface 50 and flange surface 52. For this purpose, the cutting insert 10, which is arranged in the cassette 32, is moved along the running surface 50 and the flange surface 52 by the machine tool, while the traction wheel 48 is actively rotated about its axis of rotation D. The cutting insert 10 cuts along the running surface 50 and the flange surface 52 with one of its cutting edges 18, 22, 24 to remove the worn material 54. The worn material 54 may consist of cracks, chipping, material displacements or flat spots in the running and flange surface 50, 52.

[0039] This reworking process is repeated until the pulley 48 reaches a predetermined minimum dimension / profile on its circumference, at which point the pulley 48 is replaced to ensure safety.

[0040] In Fig. Figure 10 shows the removal at a later time B, whereby the cutting insert 10 has already removed approximately half of the worn material 54 from the running surface 50 of the pulley wheel 48.

[0041] In Fig. At point C, the cutting insert 10 reaches the transition area from the running surface 50 to the flange surface 52. The worn material 54 is particularly thin in this area, yet the cutting insert 10 can process this area without difficulty. Due to the specific angular position of the receiving pocket 34 relative to the basic orientation G of the cassette 32, the cutting edge 18, 22, 24 used on the workpiece 48, for example, cutting edge 22b, is generally at a steep angle.

[0042] The semicircular shape of the cutting edges 22, 24 results in a defined line contact between the cutting edge 22, 24 and the workpiece surface 48, independent of the relative position of the cutting insert 10 to the workpiece 48. This allows for particularly precise machining of the workpiece 48, as good chip control and depth of cut control are ensured.

[0043] When the cutting insert 10 reaches the central position of the wheel flange surface 52, the holder 46 is moved so that the other cutting insert 10, which has a different orientation within the holder 46, is used. Due to its orientation within the holder 46, the other half of the wheel flange surface 52 can be processed with the other cutting insert 10, without the holder 46 obstructing the removal of the worn material 54.

[0044] In general, the angular position of the receiving pocket 34 in the cassette 32 and the semi-circular cutting edge design ensure that good chip control is possible even at shallow cutting depths.

[0045] In the Fig. In the position shown in Figure 9, the cutting insert 10 even partially rests with one of its edges 18, 20 against the worn material 54 and supports chip removal. The worn material 54 is only roughly removed by the edges 18, 20, which is why the chip-guided steps 30 associated with the edges 18, 20 are typically structured differently than the chip-guided steps 28 associated with the cutting edges 22, 24. However, the edges 18, 20 do not come into contact with the final contour of the workpiece 48. This occurs exclusively via one of the cutting edges 22, 24. The edges 18, 20 are therefore not referred to as cutting edges within the meaning of the invention, even though they roughly remove the worn material 54. Also in the figure shown in Fig.In the position shown in Figure 11, the corresponding edge 18, 20 does not lie against the end contour of the workpiece 48. This is guaranteed by the semicircular cutting edges 22, 24 and the relative orientation of the receiving pocket 34 to the basic orientation of the cassette 32, or by the angle α that the main contact surface 36, the transverse axis QS, the transverse axis Q and the side surfaces 16a, 16d each have to the axis of rotation D.

[0046] Furthermore, the cutting insert 10 can be provided with different cutting depths and chip control features, for example, a cutting insert 10 with four different chip control steps 28 on the four cutting edges 22, 24, so that this cutting insert 10 covers a very wide range of cutting conditions. The same applies to the chip control steps 30 assigned to the edges 18, 20.

Claims

[1] Cutting insert (10) for profile turning, in particular for wheel profile turning, comprising a top surface (12), a bottom surface (14) and side surfaces (16), wherein at the transition from the top surface (12) to the side surfaces (16) two cutting edges (22a, 22b) for machining a workpiece (48) and two further edges (18a, 18b) each with two ends (18a', 18a'', 18b', 18b'') are formed, wherein the two cutting edges (22a, 22b) are each formed as partial circles without interruption and have a full radius, wherein each of the two cutting edges (22a, 22b) covers an angular range of approximately 180°, so that a defined line contact results between each of the cutting edges (22a, 22b) and a workpiece (48) to be machined, which is independent of the relative position of the cutting insert (10) to the workpiece (48), wherein the cutting edges (22a, 22b) each extend from one end (18a', 18a'', 18b', 18b'') of one of the two edges (18a,18b) to the opposite end (18a', 18a'', 18b', 18b'') of the other of the two edges (18a, 18b), wherein the transition from the underside (14) to the side surfaces (16) is formed analogously to the transition from the top surface (12) to the side surfaces (16), so that the cutting insert (10) comprises four semicircular cutting edges (22a, 22b, 24a, 24b). [2] Cutting insert (10) according to claim 1, characterized by , that the edges (18a, 18b) are straight, in particular parallel to each other. [3] Cutting insert (10) according to any one of the preceding claims, characterized by , that the upper and / or lower surface (12, 14) is mirror-symmetric with respect to its central longitudinal and / or transverse axis (L, Q), in particular point-symmetric with respect to the center (M). [4] Cutting insert (10) according to any one of the preceding claims, characterized by, that the cutting insert (10) is mirror-symmetric with respect to its central longitudinal and / or transverse axis (LS, QS), in particular point-symmetric with respect to the center point (MS). [5] Cutting insert (10) according to any one of the preceding claims, characterized by , that in the side surfaces (16) on which the edges (18a, 18b) are formed, an opening (26) is provided which cooperates with a fastening mechanism. [6] Cutting insert (10) according to any one of the preceding claims, characterized by , that chip-breaking steps (28, 30) are provided on the semicircular cutting edges (22a, 22b, 24a, 24b) and / or on the edges (18a, 18b). [7] Assembly comprising a cutting insert (10) according to one of the preceding claims and a cassette (32) which can be attached to a machine tool and comprises a receiving pocket (34) for the cutting insert (10) with which a workpiece (48) having a rotary axis (D) can be machined, wherein the receiving pocket (34) has a main contact surface (36) against which a side surface (16) of the cutting insert (10) rests, wherein the main contact surface (36) has a plane angle (α) greater than 90° to the rotary axis (D) of the workpiece (48), in particular a plane angle (α) of 93°. [8] Assembly according to claim 7, characterized by , that the cassette (32) has a second mounting surface (38) which is perpendicular to the main mounting surface (36). [9] Assembly according to claim 7 or 8, characterized by , that a part (43) of a fastening mechanism for fastening the cutting insert (10) is provided on the main mounting surface (36). [10] Assembly according to claim 9, characterized by , that the central axis of part (43) of the fastening mechanism has an angle different from 90° to the main mounting surface (36).

Images